trauma survivor with an exaggerated and relatively unchecked amygdala-driven fight-or-flight stress response.

CONCLUSIONS

Characterized by symptoms of hyperarousal, numbing or avoidance, and re-experiencing of a traumatic event, PTSD may be evident shortly after exposure to the traumatic event or take years to produce symptoms sufficient to meet the diagnostic criteria; once developed, the symptoms may persist for many years. PTSD (or symptoms associated with it) has been reported in veterans from World War II, the Korean War, the Vietnam War, the Gulf War, and OEF and OIF. The prevalence of PTSD in the Vietnam War, Gulf War, and OEF and OIF have been estimated to be 14-19% (lifetime), 5-9% (lifetime), and 12-16% (current), respectively. Across a variety of precipitating events, women have twice the PTSD prevalence as men both in veteran populations and in the general population. In the general population, the prevalence of lifetime PTSD is estimated to be about 5% for men and 10% for women. The prevalence of PTSD in veterans increases as combat exposure increases, in some cases showing a linear dose-response relationship. PTSD is also highly comorbid with other psychiatric disorders, particularly major depression, general anxiety disorder, and substance-use disorders. PTSD is also associated with more disability and impaired functioning in veterans.

Although military personnel may be exposed to identical stressors during their deployment to a war zone, their short-term and long-term responses to those stressors vary. The variation is due to a host of individual risk and protective factors that influence the likelihood of long-term health effects after exposure. The committee found that among the most significant risk factors for PTSD or other psychiatric disorders are being in combat and being physically wounded. Other important risk factors include childhood maltreatment, the presence of a pre-existing psychiatric disorder, poor social support on homecoming, negative coping styles, being a minority, and a lack of hardiness. Protective factors include better education, higher military rank, having a stable family life, and having a sense of control.

Research has shown heightened sympathetic nervous system activation in people with PTSD, which includes increased excretion of epinephrine and norepinephrine. PTSD subjects respond to a variety of stressors with greater increases in catecholamines than do healthy controls. Pre-existing low cortisol is associated with increased risk of PTSD, and most PTSD studies demonstrate physiologic alterations consistent with enhanced feedback inhibition of the HPA axis and increased HPA reactivity. PTSD has also been associated with a lack of fear extinction after trauma.

REFERENCES

Aldwin CM, Levenson MR, Spiro A 3rd. 1994. Vulnerability and resilience to combat exposure: Can stress have lifelong effects? Psychology and Aging 9(1):34-44.

APA (American Psychiatric Association). 2000. Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR). Washington, DC: American Psychiatric Publishing Association.



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